How to set up an engine service schedule by running hours (and stop missing intervals)

Why calendar reminders fail on boats

A boat that did 40 hours in June and 400 in August cannot be serviced on a calendar. Manufacturers specify most engine and generator work by running hours — 250, 500, 1,000 — with a calendar backstop (for example 'every 250 hours or 12 months, whichever first'). A schedule that ignores either half misses services.

Step 1 — take the intervals from the manual, not from memory

List every hour-based item per unit: oil and filter, fuel filters, impeller, zincs, belts, valve clearance, coolant, aftercooler, injectors, turbo inspection. Give each its hour interval and its calendar backstop. Do the same for generators; they usually run more hours than the mains.

Step 2 — decide how hours get recorded

The interval is only as good as the hour reading. The reliable pattern is to capture hours as part of something crew already do — the pre-sail or end-of-day checklist — rather than as a separate job nobody owns. Once a week is fine for a cruising boat; every trip for a charter boat.

Step 3 — set 'due soon' thresholds

Decide how far ahead you want warning. 25 hours or 30 days before due is a sensible default: enough time to order filters and book a slot, short enough that the warning is real.

Step 4 — log the service against the unit, with what was used

When the service is done, record the date, the hours, who did it, and the parts and consumables used. That entry becomes the next interval's starting point and your parts usage history — which tells you what to keep in spares.

Doing it in iVessel

Each engine and generator has its own schedule of hour- and date-based services. Hours entered from the pre-sail checklist update every schedule at once; Boat Health shows OK / due soon / overdue per item and per boat; logging a service records the parts used and deducts them from spares. The whole thing prints as a service history.